00:01
We are looking at a binomial distribution.
00:03
N, the number of trials, is 9.
00:05
P, the probability of success, is 0 .5.
00:08
We want probability the number of successes x is equal to 5.
00:13
So you have three options for solving this.
00:15
First is the binomial formula, which i will use.
00:18
Second is the table in the back of the textbook for the binomial.
00:23
Third is some form of technology, like excel.
00:26
The binomial formula is the probability of exactly x successes is n choose x p to the x 1 minus p to the n minus x.
00:38
So here we have five successes, four failure states.
00:44
And i'm going to give these names, trial a, trial b, trial c, and so on.
00:51
These are independent trials, so i can combine their probabilities by just multiplying.
00:56
This term is for the successes, probability of 0 .5, multiply it by itself five times...